In a statement, Gen. Allen said he had ordered an investigation into a report that International Security Assistance Force (ISAF) personnel there "improperly disposed of a large number of Islamic religious materials, which included Qurans."

Several Qurans were put out with the airbase trash on Monday night and taken to a pit to be incinerated, where Afghan employees noticed them, the head of the provincial council, Ahmad Zaki Zahed, told the Associated Press.

Allen assured that the force's commanders "immediately intervened and stopped" the disposal, and promised action would be taken to ensure that it never happens again.

"I assure you, I promise you: this was not intentional in any way," he said. "I offer my sincere apologies for any offense this may have caused, to the president of Afghanistan, the government of the Islamic Republic of Afghanistan, and most importantly, to the noble people of Afghanistan."

Agence France Presse described the statement – which was shown repeatedly on Afghan television – as "remarkably candid." It appears to be an attempt at damage control after an incident that has the potential to cause grave offense to Muslims.

Angry crowds outside Bagram were heard to chant "Death to America" and "We don't want them anymore," the New York Times reported. Protesters threw slingshots and petrol bombs, according to an AFP photographer, who said airbase guards fired back rubber bullets.